This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The central hypothesis of this project is that circle of Willis anomalies correlate with alterations in cerebral hemodynamics and contribute to migraine susceptibility and ischemic complications of migraine. This project uses ASL, transit time mapping, high resolution MRA and fMRI to study the structural variation of Circle of Willis and associated functional changes in migraine patients compared to matched controls.